Process for producing two component crimpable regenerated cellulose fiber



Apnl 26, 1966 R. WOODELL 3,248,466

PROCESS FOR PRODUCING TWO COMPON T CRIMPABLE REGENERATED CELLULOSE F ER Original Filed 001;. 30, 1958 2 Sheets-Sheet l Big.

INVENTOR RUD OL PH WOODELL mwl w y ATTORNEY April 26, 1966 R. WOODELL 3,243,465

PROCESS FOR PRODUCING TWO COMPONENT CRIMPABLE REGENERATED CELLULOSE FIBER Original Filed 001;. 30, 1958 2 Sheets-Sheet 2 INVENTOR RUDOLPH WOODELL BY RMWJ iQ United States Patent 3,248,466 PROCESS FOR PRODUCING TWO COMPONENT CRIMPABLE REGENERATED CELLULOSE FIBER Rudolph Woodell, Kiuston, N.C.,.assignor, by mesne assignments, to Beaunit Corporation, a corporation of New York Original application Oct. 30, 1958, Ser. No. 770,656, now Patent No. 3,097,414, dated July 16, 1963. Divided and this application Oct. 15, 1962, Sci- No. 241,095 Claims. (Cl. 264-171) This application is a division of my copending application, Serial No. 770,656, filed October 30, 1958, now

US. Patent No. 3,097,414.

This invention relates to a process for producing novel and useful crimpable rayon fibers.

The production of crimpable filaments by extruding two or more viscoses, having different shrinkage potentials, through the same spinneret hole is known. While these multieomponent filaments are superior in certain respects to single component filaments, i.e., inease of crimping and crimp retentiomthe'y are deficient in other characteristics such as abrasion resistance and resistance tosoiling.

It is an object of this invention to provide a process for producing a new and useful crimpable viscose rayon fiber.

Another object is to provide a processforproducing a crimpable fiber which crimps readily in water and has excellent crimp retention, abrasion resistance and resistance to soiling.

These and other objects will become apparentin the course of the following specification and claims.

In accordance with the present invention a viscose rayon fiber is provided consisting of two components, a first component having a transverse cross-section characterized by a smooth substantially uncrenulatedcontour and a thick, preferably at least 80% skin, and a second I component having a transverse cross-section characterized by a smooth contour and acore surrounded by a skin,

the percentage of skin in the second component being substantially less than the precentage of skin in the first component and the two components being fused together along their entirelength to form a single coherent fiber. Preferably the second component has at least about 20% less skin than the first component. It is also preferable that each component is substantially oval in shape and the two components are joined in such manner that their long axes, if extended to intercept one another, form a T.

The process for forming the yarn described above comprises preparing two viscoses, A and B, adding to viscose A a small amount of cyclohexylamine as a coagulation modifier, extruding the two viscoses simultaneously in side-by-side relationship through the same spinneret hole into the coagulating and regenerating bath containing from about 6.5 to about sulfuric acid, from about 12 to about 23% sodium sulfate,.at leastabout 5% zinc sulfate, and a small amount of cyclohexylamine, viscose A having a salt index of at least 5, viscose B having a salt indexof at least 2, and stretching the yarn. Preferably the salt index of viscose A is at least 3 units higher than that of viscose B.

FIGURE 1 is an exploded view of a device useful in the extrusion of the yarn of the present invention.

FIGURE 2 is a rear view of the equalizer and separator section of the device illustrated in FIGURE 1.

FIGURES 3 and 4 are illustrations of the yarn cross sections produced as described in Examples I and III respectively.

The following examples are cited to illustrate the invention. They are not intended to limit it in any manner. The apparatus used in each example is that shown in FIGURE 1. The yarn produced is extruded through the orifices 1 of spinneret plate 2, the said plate being positioned against the equalizer and separator section 3 by means of internally threaded spinneret adapter 4, flange 5 of the spinneret plate being held against the front face of the equalizer and separator section by the face 6 of the said spinneret adapter. Concentric cylindrical separator rings 7 extend through the equalizer and separator section, the said rings being supported by the pressure equalizer plate 8 (shown in FIGURE 2) which holds them in fixed relation to the circumference of the said equalizer and separator section. The concentric cylindrical separator rings are beveled to a sharp edge which extends beyond the engaging threads of the equalizer and separator section to such an extent that when the spinneret plate 2 is positioned as previously described the sharp edges of the separator rings are immediately ad jacent to the back face of spinneret plate 2 and so arranged that each edge bisects each orifice in a particular ring of the said orifices. Pressure equalizer plate 8 (FIGURE 2) contains concentrically arranged holes 9 fitting into spaces between the concentric separator rings previously described and act to control the pressure of, and prevent pressure surges in, viscose delivered to the spinneret plate. Pressure equalizer plate 8 fits by threaded means onto a concentric conduit 10 which contains openings 11 through which various vscoses may be pressure fed to the system.

Example I Two viscoses, A and B, are prepared in the conventional manner. Viscose A containing 8% recoverable cellulose, and 7% alkali, calculated as sodium hydroxide, is prepared from cotton linters pulp using 30% carbon disulfide based on the air dry weight of the pulp. Sulficient cyclohexylamine is added to the viscose during the mixing operation to give a concentration of 0.15% by weight. Viscose B is prepared in an identicalfashion except that the cyclohexylamine isomitted. Viscose A is ripened to a salt index of 8.3 and a viscosity of 40 poises while viscose B is ripened to a salt index of 2.7 and a viscosity of 45 poises. Viscoses A and B are then supplied by means of separategear pumps, each having a delivery of 158 g.p.m. to alternate openingsof a concentric conduit as illustratedin FIGURE 1. In this manner the two viscoses are extruded through each of the spinneret holes in side-by-side relationship by means of the separator rings and pressure equalizer assembly. A spinneret of 1 inches diameter having 250 holes of 0.008 inch diameter arranged in three concentric circles, the diameter of the circles being /2 inch, 1 inch, and 1 /2 inches respectively is employed.

The viscoses are extruded into a coagulating and regenerating bath containing 9.0% sulfuric acid, 17.5% sodium sulfate, 9.5% zinc sulfate, and 0.1% cyclohexylamine, the temperature of the bath being 60 C. The filaments are lead for a distance of 31 inches through the bath, then over a Y convergence guide and for afurther distance of 119 inches, the yarn being confined in the bath by means of a series of roller guides. By means of tension type roller guides, the yarn is stretched 29% between the spinneret and wind-up based on jet velocity and wind-up speed. The yarn is led upwardly from the coagulating bath to and around a power-driven feed wheel, then downwardly'to a centrifugal spinning bucket where it is wound into a cake in the conventional manner. The peripheral speed of the feed wheel is 50 y.p.m. The yarn is purified and dried in the conventional manner. Thereafter it is passed through a slashing machine where it is treated witha hot aqueous finish solution, stretched 12% andthen dried under tension and wound onto pirns.

The yarn filaments are examined by cutting thin transv roller guides.

, ventional manner.

.denier per filament.

these cross sections and examining them under high magnification. The cross sections are dyed following the method described by Morehead and Sisson, Textile Research Journal, 15, 444- (1945) except that pontamine yellow dye is substituted for calcomine yellow dye. Measurements made on ten filament cross sections selected at random give an average of 90% skin for one portion of the cross section while the other portion had an average of 57% skin. Both parts of the cross section are substantially uncrenulated and shaped as illustrated in FIGURE 3. The filament denier of the finished yarn is 22 denier per filament. When the yarn is placed in water at 90 to 100 C. in a relaxed state followed by drying in a relaxed state, it is found that the yarn has an excellent crimp. On repea-ted wetting and drying of the yarn, the crimp is retained Two viscoses, C and D, are prepared, viscose C being prepared in the same manner as viscose A of Example I and viscose D being prepared in the same manner as viscose B of Example I. Viscose C is ripened to a salt index of 8.0 and a viscosity of 81 poises While viscose D is ripened to a salt index of 2.7 and a viscosity of 95 poises. The two viscoses are then supplied to a common spinneret by means of separate gear pumps, each having a delivery of 58.1 g.p.m. The viscoses are extruded through a spinneret of 1 inch diameter, having 120 holes of 0.008

- inch diameter arranged in two concentric circles, the diameter of the circles being inch and 4 inch respectively. The two viscoses are extruded through each of the spinneret holes as described in Example I into the coagulating bath of Example I. The filaments are led for a distance of 44 inches through the bath, then over a Y convergence guide and for a further distance of 170 inches, the

yarn being confined in the bath by means of a series of The yarn is then led upwardly from the coagulating bath to a first power driven feed wheel, then to a second power driven feed wheel rotating at the same speed as the first but having a sufliciently larger diameter to stretch the yarn 46% A hot aqueous solution containing 2.0% sulfuric acid, 3.9% sodium sulfate and 2.1%

zinc sulfate at a temperature of 93 C. is jetted onto each of the feed wheels at the top. By means of a snubber roller in combination with each feed Wheel, the yarn is given a sufiicient number of passes around the feed wheel to give the yarn a travel of 160 inches in this area. The yarn is led from the second feed wheel, which has a peripheral speed of 50 y.p.m., downwardly to a centrifugal spinning bucket Where it is wound into a cake in the con- The yarn is purified and dried in the conventional manner. Thereafter it is passed through a slashing machine where it is first passed through a hot aqueous finish solution, stretched 12% and then dried under tension and wound onto pirns. The yarn denier is 2400.

When the yarn is relaxed in a hot water bath at 90 to 100 C. and then dried in a relaxed state, it has an excellent crimp. When the yarn is fabricated into a tufted carpet, the results are substantially the same as found in Example I with filament cross sections substantially the same as in Example I. The filament denier of the finished yarn is 20 denier per filament.

exactly as described in Example II except that each viscose is extruded at a rate of 72.8 g.p.m. to give a yarn of 25 On examination of the filament cross 1 component formed from the modified viscose.

sections as described in Example I, the skin in one portion of the cross section is found to amount to 77% of the total area on the average while in the other portion of the cross section 44% of the total area is skin. The two portions of the cross section are substantially uncrenulated and the shape of the cross sections are substantially as shown in FIGURE 4.

When the yarn is relaxed in hot water at -l00 C. and then dried in a relaxed state, it has an excellent crimp. When the yarn is fabricated into tufted carpets, the results are substantially the same as found in Example I.

The foregoing examples illustrate the advantages of the novel and useful crirnped fibers of the present invention. By providing a filament having a relatively thick skin as compared to the crimped yarns of the prior art, the strength and abrasion resistance of the fiber is improved, while the smooth substantially uncrenulated contour leads to improved resistance to soiling. In addition, the unique shape of the cross section provides relatively high bulk.

The essential factor in producing the fibers of this invention is the extrusion of two viscoses, one containing cyclohexylamine modifier and the other containing no modifier, into a coagulating and regenerating bath containing a small amount of cyclohexylamine modifier and a substantial concentration of zinc sulfate. The combination of modifier in the viscose and in the bath gives one component of the filament a heavy skin and a non-crenulated contour while the other component has a much thinner skin but still has a substantially non-crenulated contour due to the action of the modifier in the bath. The zinc salt in the bath is required since the coagulation modifier is not effective in its absence.

The amount of cyclohexylamine required in the viscose will vary depending upon the viscose composition, the coagulating bath composition and other factors. However, in general it is desirable to have at least 0.05% present. Too much modifier in the viscose should be avoided for reasons of economy and to avoid spinning diificulties. For optimum results, the amount of modifier in the viscose should be adjusted to the level required to give from about 90 to about skin in the cross section. This can usually be accomplished by using concentrations in the range of from about 0.1 to about 0.25%, although under some conditions it may be desirable to use larger amounts in the range of from about 0.5 to about 1.0%.

The minimum amount of cyclohexylamine modifier in the coagulation bath should be at least about 0.05% and the amount used should be regulated in relation to the amount used in the viscose so that the skin thickness of the filament component formed from the unmodified viscose is substantially less than the skin thickness of the filament The amount required for this purpose will vary depending on the composition of the coagulating bath, the amount of modifier used in the viscose and other conditions but ordinarily will fall in the range of from about 0.05 to about 0.25%. The regulation of the modifier in the bath is easily accomplished by one skilled in the art. Since the cyclohexylamine added to the viscose is leached from the spinning filaments into the bath, it is usually not necessary to add the material directly to the bath. In some cases, however, it may be desirable to remove part of the cyclohexylamine from the bath in order to avoid unduly high concentrations. This may be conveniently accomplished by carbon adsorption as described in US. 2,787,-

' 6-18 or byother suitable methods.

The composition of the viscoses used in the process of this invention is not critical. Viscoses produced with from about 27 to about 43% carbon disulfide based on the dry weight of the pulp used are satisfactory. The .viscose may contain from about 5.5 to about 9.5% recoverable cellulose and from about 4.0 to about 8.0% alkali calculated as sodium hydroxide. The ripeness or maturity of the viscose at spinning may vary from about 5 to about 15 units as measured by the salt index method for the viscose containing the cyclohexylamine modifier and from about 2 to about 15 salt index units for the other viscose. It is preferable, although not essential, that the viscose containing the cyclohexylamine modifier have a salt index at spinning about 3.0 units higher than the other viscose.

C-oagulating and regenerating baths suitable for use in the present invention may contain from about 6.5 to about sulfuric acid, from about 12 to about 23% sodium sulfate and at least about 3% zincsulfate in addition to the cyclohexylamine modifier. Other metal salts which may supplement the action of the zinc sulfate may be added if desired. The acidity of the bath should be regulated to as low a level as is commensurate with satisfactory spinning.

The yarn should be stretched at least about 40% while passing through the bath. Where a hot secondary bath is used, the stretch may be concentrated in this bath or it may be divided between the two baths as may be desired.

After the yarn leaves the bath, it is wound into a cake in a centrifugal spinning bucket or wound on a bobbin and thereafter purified and dried in the conventional manner.

After purification, the yarn is preferably given additional stretch after thorough wetting and is then dried in the stretched condition. The stretching is conveniently applied by passing the yarn through a slashing machine of the type used in the production of tire cord ya-rn. If the customary aqueous finish is applied to the yarn, the yarn is wetted with this before stretching.

The yarn crimps readily when allowed to relax in hot water followed by drying in a relaxed state. Instead of Water, various aqueous solutions as are well known in the art may be used in the crimping operation.

While the process of this invention is suitable for producing low denier per filament yarns, it is particularly advantageous in the production of high denier per filament, i.e. above 10 d.p.f., water crimpable yarns.

The fibers of this invention may be used wherever rayon fibers are customarily employed. However, they are particularly suitable for the production of tufted carpets and cut pile fabrics.

Many modifications of the invention described herein will be apparent to those skilled in the art from a reading of the above without a departure from the inventive concepts.

What is claimed is:

1. A process for producing integral two component rayon fiber in which the extended long axes of the substantially oval components intercept to form a T which comprises essentially extruding simultaneously in side-byside relationship through the same substantially circular spinneret hole a first viscose having a salt index of at least 5 and containing from about 0.05% to about 1% by Weight of cyclohexylamine as a coagulation modifier, and a second viscose having a salt index of at least 2 and containing no coagulation modifier, into a coagulating and regenerating bath containing from about 6.5% to about 10% sulfuric acid, from about 12% to about 23% sodium sulfate, at least about 5% zinc sulfate, and at least about 0.05 by weight of cyclohexylamine, and stretching the yarn during the coagulating and regenerating step.

2. The process of claim 1 wherein from about 0.05 to about 0.25% cyclohexylamine is added to the first viscose.

3. The process of claim 1 wherein the coagulating and regenerating bath contains from about 0.05% to about 0.25% cyclohexylamine.

4. The process of claim 1 wherein at least about 40% stretch is applied to the yarn.

5. The process of claim 1 wherein the salt index of the first viscose is at least 3 units higher than that of the second viscose.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 11/1939 Great Britain. 10/1939 Japan.

ROBERT F. WHITE, Primary Examiner.

MORRIS LIEBMAN, ALEXANDER H. BRODMER- KEL, Examiners. 

1. A PROCESS FOR PRODUCING INTEGRAL TWO COMPONENT RAYON FIBER IN WHICH THE EXTENDED LONG AXES OF THE SUBSTANTIALLY OVAL COMPONENTS INTERCEPT TO FORM A T WHICH COMPRISES ESSENTIALLY EXTRUDING SIMULTANEOUSLY IN SIDE-BYSIDE RELATIONSHIP THROUGH THE SAME SUBSTANTIALLY CIRCULAR SPINNERET HOLE A FIRST VISCOSE HAVING A SALT INDEX OF AT LEAST 5 AND CONTAINING FROM ABOUT 0.05% TO ABOUT 1% BY WEIGHT OF CYCLOHEXYLAMINE AS A COAGULATION MODIFIER, AND A SECOND VISCOSE HAVING A SALT INDEX OF AT LEAST 2 AND CONTAINING NO COAGULATION MODIFIER, INTO A COAGULATING AND REGENERATING BATH CONTAINING FROM ABOUT 6.5% TO ABOUT 10% SULFURIC ACID, FROM ABOUT 12% TO AOUT 32% SODIUM SULFATE, AT LEAST ABOUT 5% ZINC SULFATE, AND AT LEAST ABOUT 0.05% BY WEIGHT OF CYCLOHEXYLAMINE, AND STRETCHING THE YARN DURING THE COAGULATING AND REGENERATING STEP. 